Pellegrini's preferred option so far this season has been Sergio Aguero and Edin Dzeko starting, but Alvaro Negredo's performances off the bench - including goals against Cardiff City and Hull City - have put him in line for a starting spot.
Pellegrini is hopeful that both Dzeko and Negredo can maintain their early-season form, while also keeping the door open for Stefan Jovetic, who is yet to make his debut for the club, to earn a spot in the starting lineup.
"No, I don't know exactly [what my best strikeforce is]. We have four important players for that combination. Alvaro Negredo is always a very important option, Edin Dzeko is exactly the same," Pellegrini told PA.
"They are different players but they are both very good players, so the important thing is how useful both are for the team. They have competition always for a place but they can play together also, so they are two important players for the team.
"We have to play seven games in 21 days, so the most important thing is not the 11 that start, but the performance of each player in every game. All the players we have, if they give a high performance, have the option to play."
City have won two and lost one of their opening three matches to the new Premier League season and will face Stoke City this weekend.